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The Mad Fermentationist

Monday, July 19, 2010

One of the great things about running this blog is that every once in awhile a reader sends me interesting information (the occasional tasty commercial beers and homebrews are a nice perk as well). About a year ago I got an email (thanks Ethan) detailing the production method employed by one of the more secretive (and larger) sour beer producers in America. The information may not be 100% accurate, the source was a tour guide at the brewery, but the concept made enough sense and the details were specific enough that I had to give it a shot. The owner of the brewery has always shied away from giving details on his souring process when interviewed, so I’ll grant them the courtesy of not coming out and naming them.

The basic idea is to sour the wort quickly before the primary Saccharomyces fermentation rather than slowly afterward. To achieve this the wort is "spontaneously" fermented with microbes cultured from malt. Before the primary yeast is pitched the wort is pasteurized to kill the lactic acid bacteria and anything other microbes. This is much faster and more controllable than the more traditional practice of letting successive waves of yeast/bacteria work for a year or more to produce a sour beer. This "sour-worting" method also eliminates most of the problems (inconsistent souring, off-flavors, stuck sparges etc...) associated with sour mashing, the other "quick" souring method.

While you could simply add crushed malt to the wort for inoculation, the process calls for adding malt to a small starter and incubating it warm to encourage the growth of Lactobacillus. Once the starter is finished the liquid is pitched into the wort, which is left warm for several more days to sour. After the wort is adequately sour it is pasteurized and fermented as usual. While the method does not produce the same complex ester and phenol profile of a traditional mixed fermentation it does produce a sour beer in just a few days longer than it takes to make a "clean" batch of beer. The finished beer is also wild-microbe-free so you don't have to worry about contaminating your kegging/bottling equipment.

For my first attempt I used the technique to add some tartness to to a recipe that borders between a low gravity English Old Ale and a Belgian Oud Bruin. Sour-worting would also be a good choice for a fruit beer or any other style that doesn't rely on the bugs for complexity.

I made the starter by combining 1 pint of 1.033 DME wort (boiled then chilled to 110 F) with 1/2 cup of crushed Maris Otter (the grain only serves as the source of lactic acid bacteria, so any base malt will do). I used a funnel to get the wort and grain into a 750 ml bottle and wrapped the make-shift fermenter with a heating pad set to high to keep it between 110 and 120 F (essentially the same setup I use to make yogurt). After 48 hours a small white krausen/pellicle formed and the starter smelled like tart apples. When I do this again I'll use an airlock to prevent any aerobic microbes from getting established, but I didn't have any issue with aluminum foil over the mouth of the bottle.

After 3 days I proceeded with the mash and sparge, which were completed as usual. After the sparge I took 2.5 gallons of the 1.050 pre-boil wort and heated it just to a boil before chilling to 80 F and pitching the starter (most of the grain had sunk to the bottom so it was easy to pour off ~1 cup of the microbe rich liquid). I flushed the carboy with CO2 before and after filling to get rid of any oxygen needed by acetobacter and other anaerobes (Cambridge Brewing played flushing with argon because it is heavier than air to keep oxygen away from their sour mashes).

The rest of the wort was boiled as usual and hopped with all of the hops for the entire batch. This wort was chilled to 65 and pitched with a packet of S-04. I may have pitched a bit more yeast than was needed, but for 2.5 gallons of 1.070 beer it wasn't too far off.

After 3 days held around 80 F ambient the portion that got the sour starter had developed the same white pellicle/krausen the starter had, as well as a similar tart aroma. The flavor was sour, but still clean (although it took a long soak in PBW and hot water to remove the slightly murky smell from the Better Bottle). I was surprised to see the gravity had only fallen a couple points to 1.046. I added 1 gallon of water to account for boil-off (I probably should have collected a bit more wort to sour). After a 30 minute boil to make sure all the microbes were dead I chilled it and racked onto the clean portion.

After two weeks in primary I racked the beer to secondary to age and added 1 oz of Hungarian oak cubes for it to sit on for a couple months before bottling. Going into secondary the character was interesting, but the flavors still need some time to blend and mellow.

Notes
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6/30/10 Dissolved 6 oz of malt extract in 3 qrts of water, added 1/4 tsp yeast nutrient. Boiled 20 min. Chilled to 110, poured into a sanitized 750 along with ~1/2 cup of crushed Marris Otter for lacto, topped with aluminum foil. Wrapped with a heating pad set to medium and left alone. Temp ~110-115 for the duration.

7/3/10 Cut of the heat, smells nicely sour, a bit fruity. Maybe a hint of vinegar, next time use an airlock.

7/4/10 Brewed by myself

Fly sparged.

Took 2.5 gallons of the pre-boil wort and heated it to a boil, chilled to 85, and siphoned into a carboy flushed with CO2, pitched the pint lacto starter (most of the grain had settled to the bottom), and flushed again with CO2.

The other 4.5 gallons boiled with all the hops. Chilled to 85, adjusted gravity 1.071, put into 38 degree fridge, then set to 64. Pitched yeast straight from the pack 4 hours later. Gave 60 seconds of pure O2.

Good fermentation on the "clean" portion after 12 hours, I over-pitched a bit.

Topped off the sour portion with 1 gallon of filtered water pre-boil (I forgot to take the evaporation of the second half into account). 30 min boil, chilled to 85, gravity ~1.040 (didn't boil off all the water I added). Mixed with the clean portion (already looked fermented out). Placed back in the fridge at 61 degrees.

Extra 1/2 gallon of the sour portion racked to a growler, pitched ~1 cup of Brett B starter. left down stairs 75-80.

8/24/10 Really produced a lot of CO2 in the keg, hopefully just the yeast getting a second wind and not an infection.

9/5/10 Took a sample, tastes pretty clean, not sure what caused all that CO2.

10/07/10 Put on tap (carb'd from the residual fermentation after kegging), nice mellow/bright acid profile with a firm oak presence.

10/14/10 Bottled 7 bottles worth of the Brett fermented portion each with 1/2 tsp of table sugar, nice and tart.

11/14/10 Ended up pretty good, but not great. The sourness is too clean for my tastes. It could use an added layer of flavor (New Glarus tends to add fruit, or smoke to the beers they brew with this method.)

11/22/10 Racked the remainder of the keg onto 1.5 lbs of Blackberries and Black Raspberries. The combo of the oak, clean lactic sourness never did it for me. Filled a 3 gallon carboy close to the top, and saved a 1/2 gallon growler clean for blending.

Blended the berry portion with 2 gallons for the bugfarm Golden Sour on soursop, and left for some additional aging.

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I modified the original technique a bit, the way I understand it all of the wort is kept together through the boil. After some or all is soured it is heated to 140 to pasteurize. I was worried that the hops would inhibit the growth of lacto (the amount wasn't specified), and I wanted to be sure the microbes were dead so I did it this way. Eventually I'll have to give this version a try, since it only has one boil instead of two.

51 comments:

fantastic post! as it is, i'm just getting into brewing sour beers (getting ready to mash the 'flanders red again' from your site) and i must say this is both awesome and disheartening at the same time. it seems a bit like cheating but i always preach about working smarter, not harder so who am i to complain? i'm definately going to try this while my first batch sours w/ the roeselare. keep up the good work and keep us posted with updates!

The way I read the original method it called for keeping all of the wort together through the boil. Souring some/all then heating to 140 to pasteurize. I was worried that the hops would inhibit the growth of lacto (the amount wasn't specified), and I wanted to be sure the microbes were dead so I did it this way. You certainly could try keeping the IBUs low and do it this way.

I don't see it as cheating, since it will give a different result than the long aged multi-microbe sour. I'm interested to see how the portion of the sour I pulled off will do with a 100% Brett fermentation, another funky time saver.

Slim, am understanding your question correctly, you are asking why I didn’t make 2.5 gallons of extract wort to sour/pasteurize rather than using half of the pre-boil wort? What would the advantage of that be? I didn't want to get half the volume of the wort from extract (both due to cost and flavor considerations).

The goal of this batch was to really to test out this new technique (if the sour half sucked I would have dumped it and just enjoyed the 2.5 gallons of clean Old Ale) before trying to sour a full batch in the same way.

I finally figured out how to post on BBB, and I posted something similar to the following:

Great post. I'm slightly biased because I'm the guy who originally emailed you regarding the approach.

I've been meaning to post something on the BBB, but I've been barely able to brew beer lately, let alone write about it.

Check out the "Fast Lacto & Brett" thread @ homebrewtalk dot com where I employed this approach with an all-Brett L primary ferment. I got a pretty damn good beer in 6 weeks.

I think my conclusions were similar to yours. I could have gone more aggressive in souring the beer...either through a higher fraction of the wort (i.e. all of it), or allowing it to ferment with the lactobacillus longer/hotter. Like you, I only got 1-2 pts drop in gravity, but was unsure how lactic acid production affects gravity readings.

Anyways, great post and topic. I'm additionally thinking about using this process in conjunction with a mixed fermentation. Seems like my sour ales don't get super sour, and this might be a novel way to boost the sourness (instead of adding lactic acid) and make a Flanders red in 6 months instead of 24. (This idea kind of dawned on me while reading the end of Raj Apte's page, where he discusses something similar.)

Here is the thread if anyone is interested (good stuff): http://www.homebrewtalk.com/f127/fast-lacto-brett-153389/ I'll certainly have to try something similar method fermenting the soured wort with 100% Brett, which should deal with the low pH. It is interesting that your soured wort had a more objectionable aroma than mine when you used a pure culture and I used grain.

I was under the impression from Wild Brews that Lacto puts out CO2 while producing lactic acid, which should lower the gravity. That said, I don't know how much CO2 is produced or if all strains behave the same way.

I too am considering it as the first step in making a mix fermented beer. Russian River Beatification and Cambridge Cerise Cassée both start with sour mashes followed by spontaneous fermentations. Seems like a good way to start playing with actual wild bugs. I’ll have to go back and read Raj’s site, I haven’t been there in awhile.

I'm curious if you could use a chemical process for the pasteurization step. Potassium Metabisulphate in the proper dose should do fine, no? Hot and cold breaks were already done. Maybe not quite the same, last year I let the mash of a big stout sour for 24 hours after making the beer. I boiled the runoff with a can of wheat extract to get a 1.040 wort that tasted like an Arnold Palmer, tea & lemonade. Added WB-06 and Brett L, but I think it would have been good with a "clean" ferment.

Ben, I used a chemical “pasteurization” on my Courage Russian Imperial Stout clone after it was fermented with Brett. In that case I wanted to make sure it didn’t get too dry. Worked, but I chilled/fined/racked/campden'd, then had to wait a few days before adding fresh yeast so it wouldn’t be killed, seems like more effort than just boiling in this case where there isn’t any/much alcohol to worry about.

Hot/cold breaks weren’t complete on this one since I hadn’t boiled it before souring, you could do them before souring though. Although, boiling drove off aromatic compounds that formed during the souring that I wouldn’t want in the finished beer.

Yeah, I have similar concerns about the 100% Brett B thing I have going with the ~1.045 remainder of the un-hopped sour wort. After two weeks there is still a huge krausen on it, but it doesn’t smell bad.

Mike, you mentioned taking steps to keep things like acetobacter at bay. I wonder if not doing so might invite a more complex sour profile, especially given the abbreviated time frame here, and if so, whether actively introducing some culture would be needed.

The problem with acetobacter is that it can get out of control quickly. Blending is the only way I’ll play with giving any of my beers extra acetic acid character. I had a starter I built up from dregs go terribly acetic (and ethyl acetate) in less than 3 day cool.

The other issue is that with this mixed culture there are all sorts of other microbes that could give you other off-flavors. Every piece of advice I’ve read on sour mashing suggest keeping oxygen away from the wort to prevent nasty aromas from developing.

"but I didn't have any issue with aluminum foil over the mouth of the bottle."

And nor should you. I work in a microbiology lab and we use foil to cover flasks of growth media that sit around for months without contamination. Although over such a long period, evaporation can be a problem.

Citing Anonymous:-"----Like you, I only got 1-2 pts drop in gravity, but was unsure how lactic acid production affects gravity readings.----"-

Ethanol fermentation lowers the gravity because ethanol has a lower density than sugar (+ mass is also lost as CO2). Lactic acid is so similar in density to sugar, that the conversion will barely affect the gravity (i.e. you can have alomost full lactic fermentation without a big shift in gravity.= hydrometer is useless! taste or use pH meter (or NaOH titration)...And as mentioned above. Pure lactic fermentation does NOT produce any CO2 = Pure (homo)lactic fermentation is "silent" (i.e. no foam/bubbles + little shift in gravity).

Another important factor will also be the following:1g glucose gives almost exactly 1g lactic acid.So if 1% w/v sugar is converted, you end up with 1% lactic acid, and I think most people (and a lot of lactobacillus) will think this is starting to be way sour enough.A drop in 1% sugar is still just a theoretical drop of 4 points....(which in this case will be almost undetectable since the densitys are so similar)

Sometimes you will have more of the heterofermenting lactobacillus, and then you will se both gas and a drop in gravity. But I rarely get heterofermenting critters when innoculating with malt and incubating at high enough temperature. On the other hand, with grain(flour) or cabbage using lower temperature, it is the other way around.

I have used this method several times before I wanted to deal with live bugs in fermenters and bottles. The last batch I went with lacto during the fermentation and I like the pre-ferment more. I've only gone 24 hours before boiling, but maybe next time I'll let it go longer.

Interesting process. I am getting a few pounds of frozen ripe nectarines soon, so I was thinking of doing a quickly soured Belgian pale or something similar that would go well with the fruit. Any suggestions on a style? Also, would 2 weeks in the secondary on the fruit be enough?

I would guess that will guess that 3 lbs in 5 gallons would give you a subtle fruit character. So it all depends on what you are looking for. You can always add more after 2 weeks if you don't have enough character.

Getting ready to brew this soon. If I wanted to sour 100% of the wort, would I heat up the wort just to boil, chill, pitch lacto starter, let it sit at 90F or so for a couple of days, then do the regular boil with hops, chill, and pitch the main yeast? Or do I boil with hops first, then chill, pitch lacto, let it sour, then pasteurize at 140F and pitch the main yeast?

That sounds more like what I saw when I've done pure culture Lacto fermentation (like my Gose). That is one of the things about doing a "spontaneous" fermentation, it is hard to control. I would guess your beer is fine.

Michael, I have been thinking about this post for months, I am ready to try a quick flanders red.Do you think I can just Boil the wort with a 60 minute hop addition, divide the wort into a pail and carboy. Pitch yeast in the pail, and crushed grain in the carboy. After a few days of souring, bring the carboy contents up to a boil, cool and add it to the pail. Would the hop addition prevent the souring from taking place?

Hops are a preservative against Lactobacillus, so they certainly could inhibit the souring process using this method. You could either go easy on the hops, or just pull half the wort for souring before adding the hop addition. Good luck, let me know what you end up doing and how it turns out.

Absolutely love your blog; it's been a great source of information and inspiration for me. I've been reflecting on this post for quite some time, and am planning a quick-soured "kriek" in a couple months based on what you did here. I'll do a sour starter as you did, which I'll pitch to the full wort. However, I'm considering waiting until after souring to do the full boil and hopping, just bringing the mash runnings to 170F to pasteurize prior to souring.

Also trying to figure out how to keep up the temp of both the starter and the wort during souring; I don't have access to an old-school heating pad that won't shut off on me, so I'm trying to figure out whether or not it's plausible to build a "hot box" with heat lamps. Any thoughts on this would be great. Thanks again for posting!

Seems like a good plan, I'd probably go a similar route if I was doing a sour fruit beer with this technique.

To keep the temp up you could do the lightbulbs if you also shielded the fermeter from the light. Alternatively you could get some of those repile ceramic heaters that plug into light sockets. Another idea would be to get a brewbelt that is designed to keep a fermenter warm during winter. Whatever you do you try it out first to make sure you don’t bake the bugs.

Well, after a few weeks in the bottle, I have to say that the beer turned out pretty well. Almost exactly like I wanted it to. It has great ripe peach and slight malt character in the aroma, the flavor has peach also, but not as strong as the aroma. The lacto fermentation resulted in tart, almost sour profile, which goes great with the peach.

Is there a reason you need to use crushed grain for the sour starter? It would seem like whole grains would be easier to remove later, although it's probably not enough grain to worry about. I just assumed all the lacto was on the outside of the husk.

Certainly don't have to, but in an old interview I heard Peter Boukaert say that he likes a complex starter for growing Lacto (tossing in spent grains etc...) so it won't hurt either.

Earlier today I had a sip of the growler I saved of this beer when the rest went onto fruit, it has come a long way in the last year. The sourness seems more integrated and the oak has calmed down, sad I didn't hang onto more.

FWIW, I made 4L worth of lacto starter. I used pils, pale, and wheat malt in 3 different growlers. I kept them in a hot shed with a brewbelt. I used whole, unmashed grains and 400g of dextrose. All three worked about the same. pH had dropped from 7.1 to ~3 within 24 hours. Maybe a slight acetic character (but I might be imagining that), but no mold/funk/off smells. They're going into the wort tonight and I plan on boiling on Wednesday.

Excellent, good luck! Keeping oxygen away from those starters (and the beer) is a good idea to keep down acetobacer and other aerobic microbes, but shouldn't be a gib deal with a quick pH drop like that.

Well, the comments above about lactic acid not affecting gravity much puzzle me. Every time I've done a souring with wort preboil, I've taken a gravity reading, and I have each time seen a significant drop in gravity.

For the Saison I made yesterday, it was on the order of over 10 points (from 1.065 to 1.050 for an overnight souring ). When I first attempted a Berliner Weisse, I went from 1.030-ish to 1.005-ish. I ended up adding DME and the beer was insanely sour, but also quite fantastic. (The pH was about 3.56 in the end, or at least, that's what my meter measured -- and in fact the pH stayed steady the last day or two of souring, so maybe it was something else going on to affect the gravity?)

In both cases, I collected wort, pitched a handful of raw, crushed grain, kept out oxygen as much as possible, and kept it warm to let it sour.

I understand lacto has a limit as far as how sour it'll get things. I understand other bugs may be acting. But my results seem to be consistent, at least in my house, and I'm wondering what could explain it. I haven't found anything yet...

It all depends on what sort of Lacto you have living on your grain. Some strains (heterofermentative) will produce a range of byproducts including CO2 and alcohol, while others (homofermentative) will just produce lactic acid without dropping the gravity much. That is part of the risk with any “spontaneous” fermentation, you can’t be sure exactly what microbes will be at work. The Bruery does their Berliner Weisse with a nearly complete Lacto fermentation (their culture has a few Brett cells as well) and it drops to ~1.002 in a month.

Ah, yeah, okay, that makes sense. Trust me, I'd be using lacto cultures but I live in South Korea and we're lucky to get liquid yeasts over here, let alone cultured strains of lacto or Brett.

The Bruery does their Berliner Weisse with a nearly complete Lacto fermentation (their culture has a few Brett cells as well) and it drops to ~1.002 in a month.

Ha, sounds like my kind of beer. But I have to wonder how much of that is sugar turned into alcohol, versus sugar turned into lactic acid. (Since, I assume, they're doing the lactic fermentation after the boil, simultaneous to the alcohol fermentation.)

And like I said, it can't be too hard to get it down to 1.004 in a month: I got a pre-boil Berliner Weisse wort down to 1.005 in three days just off lacto alone. (But it was warm, and I assume they're using a cooler temperature.)

I think the wild strains often have something on their cultured brothers, they just tend to be less easily predictable.

I don't believe lactic acid production generates CO2, so it wouldn't drive the gravity down (meaning that all of that gravity change would be alcohol production). It is pitched post-boil, just a culture they repitch (every time they analyze it there are fewer Brett cells left).

Michael, I actually found this post after buying ingredients based on your "Sour Beer Orientation" article in Nov 2011 BYO, not realizing that was you! Anyway, this thread was very helpful - I decided to go with a commercial pitch of Lacto (WY5335) to ensure I didn't get a heterofermentative variety. I made a 1/2 gallon starter and pitched it among 13 gallons of wort split among 3 carboys, topped up with co2 - for an 11-gallon yield batch. The 3-day starter, held at 93F, the high end of Wyeast's ferment range, soured nicely, as did the wort held at 91F for 2.5 days (53 hours). The wort dropped 3 points (1.053 to 1.050) after souring, partly due to the lower gravity 1.033 starter. To make up for the reduction of gravity, I added 10 ounces of light DME to the boil, and hit the desired 1.057 OG exactly after an 80 minute boil. I was concerned that I would not get the right level of sour, but the hydrometer sample tasted spot on. Can't wait to see how it ends up! I also added 19 oz. of montmorency cherry juice concentrate (Tart is Smart) to 6 gallons of the beer after a couple days of fermentation. I'll be racking to secondary on top of med toast French oak cubes in about a week. Thanks for sharing this recipe!

Sounds delicious! Hope it turns out well. It may taste a bit more sour after fermentation without the residual sweetness of the wort, but the pH will actually rise slightly as the brewer's yeast work. Always happy when I get people to try it for themselves.

Mike,Your documented experiences have been a great resource for me as I've progressed as a homebrewer. I just came across this post the other day, and it's inspired me to attempt this method in an upcoming batch. Have you played around with the method any since this post? I know you mentioned that the lacto didn't produce anything overly complex and NG typically added fruit or other elements to beers produced this way. Considering that, do you think this would be a good way to do a dry-hopped sour?

I haven't tried it, but I think this would be a great technique for making a hoppy sour. Haven't tried this method again but I may play with it a few more times to see if I can find a good way to make a quick sour beer that I am happy with.

I tried to do something similar but it didn't work out. Wanted to try it out on a 1 gallon batch, did two 200ml sour starters with DME and kept them at 38C (100F) for 3-4 days. Got great white fluffy pellicle and got very tart.

I then boiled up 2 gallon of DME wort, lightly hopped with aged hops, cooled to 38C and then pitched the sour starter into 1 gallon and half a tube of white labs Berlinner Weisse blend into the other.

Nothing happened. After 4-5 days there was still nothing except a feint, odd smell but little else. Only thing that comes to mind is that I might have read the temp wrong and baked all the bugs. I'll try it again but cool much further, pitch and then bring back up to 38C...

If you had only tried the wild Lacto, I would have said that the "light" hopping was enough to inhibit it. Aging reduces the bitterness of hops, but they are still protective against Lacto (although obviously more so at the high rate that lambic brewers use). However, with the Berliner Blend, which includes yeast as well, I'd guess something like temperature would be a more reasonable culprit.

Hey Mike,I recently tried this method and had some interesting results. I cultured what i thought was just lacto off some grain and after two days the sour portion had out preformed the clean portion in gravity drop.(clean was at 1.030 sour at 1.015, OG 1.050) So i am assuming i cultured something else other than lacto in my starter. The sour portion tasted amazing before i pasteurized and blended tasted great before going on some oak about a week ago. So my question is about what you think i cultured from the grain? kind of bummed now i didn't save any of the cake from the sour portion. O and temps were around 65 for the ferment in a steady basement environment.

I am thinking of mashing then putting all of the wort into a 5 gallon carboy then keeping it at 120 degrees for a couple of days on lacto and then boiling and fermenting with safale 05 at room temperature.

Is there a reason I shouldn't do this? I haven't read about anyone doing it on the internet. What do you think the outcome will be?

The only thing to be careful of with that technique is not letting the pH drop too low. If you get the wort much below 3.5 before the ale yeast gets going, it could have a sluggish, incomplete, or off fermentation.

Hi Mike. Love your book- I spent the holiday weekend reading it! I'm thinking of brewing a very low IBU wort, pitching some commercial lactobacillus, and then after a few days pitching some brett. Hopefully letting the lacto continue doing it's thing will add some more complex sourness over a couple of months. I'm not concerned about "contaminating" my gear as I already have a dedicated set for sours. Can I skip the pasteurization step or is there some reason (other than maintaining clean gear) that you would advice pasteurizing the wort?